If you have the means, I do so recommend picking up a bouncy castle. And I will let you in on a little secret: like many things, bouncy castles are much more fun once you start using them not as directed. For example, you might choose to ask, "what happens when you try to get on top of the bouncy castle instead of staying inside?" The answer is, "it tries to kill you!" But it's much, much more fun that way.